Beachgoers urged to report endangered leatherback turtle sightings

Endangered leatherback turtles are lured to British waters by the huge number of jellyfish, says the Marine Conservation Society

A female leatherback turtle returns to the Atlantic after laying eggs on a beach in French Guiana. The Marine Conservation Society wants the public to report turtle sightings in British waters, where they come to feed on abundant jellyfish. Photograph: Françoise Emily/Alamy

Beachgoers are being asked to look out for endangered leatherback turtles which are currently visiting UK waters to feed on the huge numbers of jellyfish.

The Marine Conservation Society (MCS) wants the public to report any turtles they see during August, the peak time to spot the creatures in UK waters, to see if there are any hotspots for them or areas where conservation measures are needed.

MCS specialists say the turtles are arriving from their nesting grounds in the Caribbean to feed on jellyfish, numbers of which, they believe, are rising, potentially providing more food for the critically endangered species.

Unlike other reptiles, says the MCS, leatherback turtles, which can weigh up to a tonne and grow to three metres (10ft) long, can maintain their own body heat up to 18C warmer than even the cold British summer seas.

This year, the Irish Sea in particular has been "turtle heaven" because of the huge numbers of jellyfish there, said Dr Peter Richardson, MCS's biodiversity programme manager and turtle specialist.

There have already been a dozen sightings, compared with a recent average of about 20 turtles a summer – but in a good year as many as 60 or 70 animals may be seen.

Richardson said the Atlantic appeared to have become the last stronghold of the leatherback. Breeding populations of turtles are increasing in the Atlantic while they face extinction in the Pacific and Indian oceans.

Their better fortune in the Atlantic could be due to conservation measures to protect their beach nesting sites, massive declines in species such as tuna which feed on baby turtles, and increasing numbers of jellyfish.

Pollution, over-fishing and climate change are among the theories for the increase in jellyfish.

"There are so many jellyfish this year, with lots and lots of reports, particularly in the Irish Sea – it's turtle heaven, there's so much food for them," Richardson said.

"We want to know where and when they occur and if there are any hotspots so we know where they are and can run any protective measures where they occur."

He added: "The leatherback is the largest of all marine turtle species and at a distance could be mistaken for a floating log, but if you approach them slowly and carefully, once you see their large reptilian head, massive flippers and ridged leathery shell you can't mistake them for anything else."